Electric heater.



UNITED STATES PATENT oFFro ELIIIU THOMSON, OF SVAMISCOIT, MASSACHUSETTS, ASSIGNOR TO GEN- j ERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

ELECTRIC HEATER.

Specification of Letters Patent.

Patented June 18, 1907.

Application led October 16,1906. Serial'No. 338,920.

whereby the energy of an electric current.

may be transformed into heat in a reliable and ell cient manner.

My invention relates' more specifically to electric heaters to be used with alternating currents.

One of the objects of'my invention is to irovide an electric heater which is ca able of being used eliciently and safely on righ, as well as low voltages, provision being made for conserving the insulation, when working at high otcntials.

It is a so one of the 'objects of my invention to meet practical conditions, and to save all possible heat by arranging compact and powerful apparatus, the insulation of which will be very high, and which will avoid lagging currents produced by too large self induction. To this end, the body in which the heat is produced is designed to act, not only as a hysteric core but also as a closed secondary, the

core being-made of the shell type and com- Eletely surrounding the coil so thatfthere will e no stray magnetism.

A further object of my invention is to produce an alternating current device of the transformer type, the construction being such that the primary coil may be kept cool as well as the secondary if desired, in order not to weaken the insulation by heating the insulating material or impair the conductivity of the coils.

Further objects of my invention will appear in the course of the following specification, in which I have shown certain specific forms merely for the purpose of illustration.

I n the drawings in which several types of my device are shown, Figure 1 represents a sectional view of one form of the invention; while Figs. 2 and 3 represent slightly modified constructions.

Referring to Fig. 1 of the drawings, 10 is the primary of the transformer, having a core 11 and a heavy secondary 12. This second ary is arranged to pass into a mass of`iron which may be of any desired construction. In this particularinstance I have shown the iron in the form of a shell 13, having tubes therein. The shell may be constructed by casting it around the pipes or tubes 14, the inlet of which may be at 15 and the outlet at 16. These tubes may be for generating steam, or heating circulating water, the circulation being across and back from the inlet to the outlet. The secondary 12 which likewise acts as a primary to the surrounding shell and tubes passesrup into these tubes in such a manner that a portion of them passes between thelegs of the secondary so as to constitute a core. This arrangement constitutes one of the important features of my invention. The hard iron shell 13 forms a shortcircuited secondary of which 12 is the primary, so as to waste energy in closed circuits parallel to the secondary coil thus generating ieat, while the core composed of tubes, which are made preferably of hard hysteretic iron, causes a loss due to hystereses. The secondary is preferably jacketed orlagged withsome non-conductor, as for instance, asbestos 1 7, so as to maintain the secondary coil as cool as possible by preventing the conduction 0f heat thereto from the casing and the core. I also endeavor to prevent the transfer of heat by narrowing or cutting away a portion of the secondary, as at 18, thus reducing the conductivity with respect to heat without materiall y interfering with the electric conduction. The shell may likewise be lagged with asbestos 19, if desired.

In Figs. 2 and 3, the arrangement is somewhat diilerent, the construction being such that the heating coil is sup orted in a space surrounded by an iron bo which in this case also forms a core. The circulation of fluid takes place through the passages as before. In this form the heating coil 2O is made to receive the current at low potentials from an ordinary step-down transformer 21. 'lhe coil may consist of a number of turns of wire and be allowed to run hot, since very little heat wil] be conducted back to the transformer through the conductor.

In Fig. 3, the coil 22 is shown supported so that there will be circulation of iuid around it. This fluid may be oil if desired, which may enter cold at 23, and after circulating around the heating coil, afterward pass to the youter portions through the tubes to receive the full amount of heat. may also be lagged if desired. It should be understood that the construction of the casing or shell may be varied as desired. in the construction shown in Fig. 3, the heater may be constructed in halves the joint being in the plane of thepaper. 1 The tubes and the inner casing 24 can be cast in one part with the outer casing.

It will be understood of course, that the forms of my invention herein shown and described are merely typical since many changes and modiications will readily suggest themselves to those skilled in the art without departing from the spirit of my invention, the scope of which is set forth in the appended claims.

What l claim as new and desire to secure by Letters Patent of the United States, is,

1. An electric heater comprising a transformer having its primary circuit embedded in a mass of hysteretic iron.

2. An electric heater comprising a transformer having its primary circuit inclosed by a mass of hysteretic iron, and tubes embedded in the iron for a heat-transmitting circulatory medium.

3. An electric heater for alternating currents, comprisinga primary coil, and a shortcircuited secondary of magnetic material provided with tubes forming a core for the primary coil.

' 4. An electric heater comprising a transformer having its primary circuit inclosed by a mass of hysteretic iron, and embedded iron tubes in said mass conveying a heat-transmitting circulatory medium.

5. An electric heater for alternating currents, comprising a primary coil and a shortcircuited secondary of magnetic material This heater i having a portion thereof arranged to form a core for the primary coil.

6. An electric heater for alternating currents comprising a primary coil, and a sliertcircuited secondary inclosmg and completely surrounding the same.

7. An electric heater for alternating currents, comprising a transformer, having a tubular short-cirr-,uited secondary, and a primary eoilmounted within the same.

8. An electric heater for alternating currents, comprising a primary coil and a shortcircuited secondary inclosing the same, and provided with tubes surrounding the primary coil.

9'. An electric heater comprising a transformer having its primary circuit embedded in a mass of iron, and a heat-insulating medium between the iron mass and the primary circuit to maintain a relatively low temperature in the rimary circuit.

10. An eliectric heater comprising a heatgenerating transformer, the primary of which is a low-resistance conductor carrying a current of large volume, and means applied to said conductor to maintain a low temperature relatively to that of the transformer.

l11. An electric heater for alternating currents, comprising a primary coil and a multitubular shortfcircuited secondary, inclosing and completely surrounding the same, a portion of said tubes forming a core for the primary coil.

In Witness whereof, I have hereunto set my hand this tWenty-ifth day of September, 1906.

ELIHU THOMSON. Witnesses:

JOHN A. MCMANUS, Jr., HENRY WESTENDARP. 

